Keeping the Raspberry Pi up-to-date with the latest version OS and installed software is quite easy.
It requires your Pi to have a network connection to the internet.
These commands will update raspian and perform a cleanup:
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
sudo apt-get clean
To perform a firmware update:
sudo apt-get install rpi-update
A reboot is required after updating the firmware.